Electronic Principles(Engineering > Computer Science And Engineering ) Questions and answers for exam Preparation

Question 1. In an intrinsic semiconductor, the number of free electrons

Impossible to say
Is greater than the number of holes
Equals the number of holes
Is less than the number of holes
None of these

Explanation:-

Answer: Option C. -> Equals the number of holes

Question 2. The rise time of a pulse waveform is the time required for the voltage to rise:

from zero to its rms value
from 10% of the peak value to 70.7% of the peak value
None of these
from zero to its peak value
from 10% of the peak value to 90% of the peak value

Explanation:-

Answer: Option E. -> from 10% of the peak value to 90% of the peak value

Question 3. A device that converts mechanical into electrical energy is?

Explanation:-

Answer: Option B. -> generator

Question 4. The total impedance of a parallel RLC circuit:

always decreases as the applied frequency increases
None of these
is maximum at the resonant frequency
is equal to the sum of the values of resistance, inductive reactance and capacitive reactance
always increases as the applied frequency increases

Explanation:-

Answer: Option C. -> is maximum at the resonant frequency

Question 5. Which one of the following kinds of materials has the lowest permeability?

Explanation:-

Answer: Option E. -> A diamagnetic material

Question 6. For a pure capacitor:

None of these
ac current leads the voltage by 90 degree
ac current lags the voltage by 90 degree
ac current and voltage are exactly in phase
ac current is converted to dc voltage

Explanation:-

Answer: Option B. -> ac current leads the voltage by 90 degree

Question 7. The component that forms the electrical connection between the rotating coil of wire in a motor and the external source of electrical energy is called the:

Explanation:-

Answer: Option B. -> commutator

Question 8. Waveforms are graphs that show:

the passage of time on the vertical axis and amplitude on the horizontal axis
amplitude on the vertical axis and frequency on the horizontal axis
amplitude on the vertical axis and the passage of time on the horizontal axis
frequency on the vertical axis and amplitude on the horizontal axis
None of these

Explanation:-

Answer: Option C. -> amplitude on the vertical axis and the passage of time on the horizontal axis

Question 9. In a pure inductor:

None of these
ac current is converted to dc voltage
ac current and voltage are exactly in phase
ac current lags the voltage by 90 degree
ac current leads the voltage by 90 degree

Explanation:-

Answer: Option D. -> ac current lags the voltage by 90 degree

Question 10. When the collector current increases, what does the current gain do?

Explanation:-

Answer: Option D. -> increases